Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) and third-generation (3G) and fourth-generation (4G) high speed data/Internet-capable wireless services. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Exemplary cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies. More recently, Long Term Evolution (LTE) has been developed as a wireless communications protocol for mobile phones and other terminals to communicate data at high speeds. LTE is based on GSM, and includes contributions from various GSM-related protocols such as Enhanced Data rates for GSM Evolution (EDGE) and Universal Mobile Telecommunications System (UMTS) protocols such as High-Speed Packet Access (HSPA).
Accordingly, communications systems and devices are becoming increasingly diverse with new technological advancements. Communications devices are now able to support various different communications technologies and protocols. For example, a wireless telecommunication service generically referred to as “Push-To-Talk” (PTT) capability can provide quick one-to-one or one-to-many communications, wherein a carrier typically establishes the recipient devices for wireless device communicating in a PTT group. For example, a PTT communication connection may typically be initiated in response to a single button-push on a wireless device, which may activate a half-duplex link between the speaker and each member device within the group, wherein the device can subsequently receive incoming PTT transmissions once the button is released. In some arrangements, the PTT speaker will have the “floor” whereby no other group member can speak while the speaker holds the floor. Accordingly, once the speaker holding the floor releases the PTT button, any other individual member within the group can engage a PTT button in order to request and thereby take the floor. Furthermore, other wireless communication services may support full-duplex Voice-over-Internet Protocol (VoIP) sessions, where communication may be allowed in both directions such that different parties can communicate simultaneously (i.e., parties on different ends can speak and be heard at the same time).
However, various conditions may result in a user involved in a half-duplex or full-duplex voice call needing to trigger a handover from a current base station to a target base station in the same access network or a different access network (e.g., user mobility, radio conditions, cell capacity, more favorable conditions in a neighbor cell, etc.). In the former case, because the current base station and the target base station are in the same access network and therefore implement the same radio access technology (RAT), the handover may be termed an “intra-RAT” handover. In the latter case, the base stations in different access networks may implement different RATs, in which case the handover may be termed an “inter-RAT” handover. However, in cases where the current and target base stations are in different access networks but implement the same RAT, the handover would also be an intra-RAT handover. In any case, if a wireless device is involved in a half-duplex or full-duplex voice call and a handover is triggered, the voice call may end if the handover delay results in inactivity leading to a dropped call and/or perceivable “clicks” due to packet loss and/or delays during the handover may result. Accordingly, depending on the target access network, handovers that are triggered while a wireless device is involved in a voice call or other real-time multimedia session may cause session interruption, packet delay, packet loss, and degraded user experience, among other problems.